JP2677113B2 - Electrofusion fittings - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a pipe to be joined such as a polyolefin pipe, and more particularly to an electrofusion joint for joining thin pipes.

[0002]

2. Description of the Related Art As a joint for joining a plastic pipe such as a polyolefin pipe used for a water supply pipe or a gas pipe, an electrofusion joint using a thermoplastic resin is used.

FIG. 4 is a sectional view showing a conventional electrofusion joint. In the figure, reference numeral 1 denotes an electrofusion joint, in which heating wires 5 and 6 are buried in the vicinity of the pipe insertion holes 3 and 4 of a pipe-shaped joint body 2 made of a thermoplastic resin such as polyolefin resin. A positioning projection 7 is formed on the inner wall of the central portion of the joint body 2.

The above electrofusion joint 1 is
As shown in FIGS. 5 and 6, by inserting the pipes 8 and 9 to be joined into the pipe insertion holes 3 and 4 from both sides and energizing the heating wires 5 and 6 for a predetermined time, the resin near the heating wires 5 and 6 is removed. Layer 1
0 and 11 are melted and fused to the pipes 8 and 9 to be joined, and the pipes to be joined are joined. In FIG. 5, the pipe insertion hole 4
Although the pipe 9 to be joined is also inserted in it, it is omitted in the drawing.

In order to obtain good joining performance in such an electrofusion joint, it is necessary to raise the temperature and pressure at the fusion-bonding interface. Particularly in the case of a thin resin pipe, as shown in FIG. When heated to a temperature required for fusion, the pipes 8 and 9 to be joined are deformed inward, the interfacial pressure is lowered to lower the fusion strength, and the deformation portion 12 narrows the flow path 13. is there.

When the pipes 8 and 9 to be joined are inserted, they are brought into contact with the projections 7 and positioned, but the pipes 8 to be joined in FIG.
In the case where the insertion is insufficient, or when the pipe to be joined 9 is obliquely cut, the interfacial pressure decreases due to the outflow of the resin and the fusion pressure decreases, and the outflow resin 15 that flows out into the gap 14 causes There are problems that the flow path 13 is narrowed and the heating wires 5 and 6 are short-circuited 16.

[0007]

SUMMARY OF THE INVENTION In order to solve the above problems, the object of the present invention is to prevent the deformation of the pipes to be joined during fusion, and to prevent the molten resin from flowing out even if the insertion is insufficient or if the pipe is cut diagonally. It is an object of the present invention to provide an electrofusion joint capable of preventing the above, thereby maintaining a sufficient interfacial pressure, obtaining a large joint strength, and preventing a decrease in the flow path and a short circuit of the heating wire.

[0008]

SUMMARY OF THE INVENTION The present invention comprises a thermoplastic resin joint body having a pipe plug-in hole, and a heating wire provided in the pipe insertion near the hole of the joint body, the pipe insertion hole and a pipe support member extending from said joint body so as to support the inner surface of the joined pipes inserted into the joint the
The body and the pipe support and the resin that constitutes the pipe to be joined
Made of compatible thermoplastic resin and support pipe
Whether the body has a higher softening temperature than the resin that constitutes the joint body
In electro fusion fitting according to claim Rana Rukoto
is there.

As the thermoplastic resin forming the joint body and the pipe support , a resin compatible with the resin forming the pipes to be joined can be used . For example, when the resin forming the pipes to be joined is polyolefin, the joint is Body and power
Polyolefin is also used as the resin forming the ip support .
Examples of the polyolefin include polyethylene, polypropylene, polybutene, poly-4-methylpentene and the like. When the resin constituting the pipe support of the joint body, or a tree fat constituting the joint body and the polybutene, because creep resistance is excellent, the thickness of the joint, can reduce the wall thickness of the pipe support, preferably .

[0010] Pipe support by using a resin having high softening point than the resin constituting the joint hand body, preventing deformation of the pipe support itself, it is possible to increase the deformation preventing effect of the joined pipes. As such resin , compatibility
High softening point thermoplastic resins having can be used.

The size of the pipe to be joined used in the electrofusion joint according to the present invention is not particularly limited, but usually the inner diameter is 5 to 50 mm,
A wall thickness of 1 to 5 mm is used. In the electrofusion joint according to the present invention, the wall thickness of the pipe support is not particularly limited, but is usually 0.5 to
It is in the range of 3 mm. The depth of the pipe insertion hole is usually 10 to 30 mm.

[0012]

In the electrofusion joint of the present invention, the pipe to be joined is inserted into the pipe insertion hole so that the inner surface of the pipe to be joined is supported by the pipe support, and the heating wire is energized to remove the resin layer near the heating wire. The pipes to be joined are melted and fused to the pipes to be joined, and the pipes to be joined are joined.

At this time, the pipe to be joined is also softened by the heat of the molten resin layer and is partially melted. However, since the inner surface is supported by the pipe support, deformation of the pipe to be joined and outflow of molten resin are prevented. It As a result, a sufficient interfacial pressure is generated to increase the bonding strength, and the deformation of the pipes to be bonded, the reduction of flow paths due to the outflow of the molten resin, and the short circuit of the heating wire do not occur.

[0014] Particularly pipe support, the use of the high softening point than the resin constituting the joint body resin, softening of the pipe support itself is prevented. Therefore, even if the temperature of the molten resin layer rises and the pipes to be joined are softened or melted, the deformation of the pipe support is prevented. This place
The surface of the pipe support will soften even if
Both the pipe support and the resin that make up the pipe to be joined
Since a soluble resin is used, the pipe to be joined and the joint
Both body and pipe support are fused and united to join
Increases strength.

[0015]

Embodiments of the present invention will be described below with reference to the drawings. FIG. 1 is a sectional view showing an electrofusion joint of a reference example, and FIG. 2 is a sectional view showing its usage state.
The same reference numerals as in FIG. 6 denote the same or corresponding parts.

The electrofusion joint 1 of this reference example has the same basic structure as the conventional one, and a pipe insertion hole of a thermoplastic resin pipe-shaped joint body 2 having pipe insertion holes 3 and 4. Heating wires 5 and 6 are buried near 3 and 4, and a protrusion 7 for positioning is provided on the inner wall of the central portion of the joint body 2.
Is formed, the pipe-shaped pipe support 21 is integrally formed from the projection 7 to the left and right side opening portions,
The inner surfaces of the pipes 8 and 9 to be joined which are inserted into the pipe insertion holes 3 and 4 are supported.

[0017] In Reference Example, polyethylene, polypropylene, relative to the joined pipes 8,9 of polybutene, phase as the resin constituting the joint body 2 and the pipe support 21
Polybutene, which is a soluble thermoplastic resin, is used. The heating wires 5 and 6 are embedded in a spiral shape so as to surround the pipe insertion holes 3 and 4.

The joint body 2 and the pipe support 21 are formed in such a shape and size as to sandwich the pipes 8 and 9 to be joined, which are inserted into the pipe insertion holes 3 and 4, from the outer surface and the inner surface. These thicknesses are the resin layers 10 near the heating wires 5 and 6,
It is determined to have a thickness capable of retaining the original shape when 11 is melted.

The above electrofusion joint 1 is
As shown in FIG. 2, the pipes 8 and 9 to be joined are inserted into the pipe insertion holes 3 and 4 so that the inner surfaces of the pipes 8 and 9 to be joined are supported by the pipe support 21, and the heating wires are energized to generate electricity. The resin layers 10 and 11 near the heating wires 5 and 6 are melted and fused to the pipes 8 and 9 to be joined, and the pipes 8 and 9 to be joined are joined.

At this time, the pipes 8 and 9 to be joined are also softened and partially melted by the heat of the resin layers 10 and 11 which are melted. However, since the pipe supports 21 are supported from the inner surface, the pipes 8 and 9 to be joined are joined. Is prevented from being deformed. Pipes to be joined 8, 9
Is brought into contact with the positioning projection 7 to be positioned,
Even when the pipe 8 to be joined is insufficiently inserted, or the pipe 9 to be joined is obliquely cut, the molten resin 22 is filled in the gap 14 and the outflow resin 15 unlike the conventional case is not generated.

As described above, since the pipes 8 and 9 to be joined are prevented from being deformed and the resin is prevented from flowing out, a sufficient interfacial pressure is applied between the molten resin layers 10 and 11 and the pipes 8 and 9 to be joined. As a result, the bonding strength increases. Therefore, the pipes 8 and 9 to be joined are not deformed, the flow path 13 is reduced due to the outflow of the molten resin, and the heating wires 5 and 6 are not short-circuited.

[0022] FIG. 3 is a sectional view showing the electro-fusion fitting according to actual施例. This embodiment is shown in FIG.
While almost the same structure as the beauty Figure 2, the pipe supporting member 21 has a compatibility with the joined pipes 8,9, and softening temperature than the resin constituting the joint body 2 is high the thermoplastic resin < and is formed by insert molding so that the rib 23 is embedded in the positioning projection 7. In the case where polybutene-1 is used as the resin forming the joint body 2 in this case, poly-4-methyl-1-pentene can be shown as the resin forming the pipe support 21.

The electrofusion joint 1 of this embodiment also joins the pipes 8 and 9 to be joined in the same manner as described above, but the pipe support 21 is made of a material having a higher softening point than the resin forming the joint body 2. Therefore, softening of the pipe support 21 itself is prevented. Therefore, even if the temperatures of the molten resin layers 10 and 11 are increased and the pipes 8 and 9 to be joined are softened or melted, the deformation of the pipe support 21 is prevented. In addition, both the joint body 2 and the pipe support 21
And are compatible with the resin forming the pipes 8 and 9 to be joined.
Since it is made of resin, the pipes 8 and 9 to be joined and the joint body 2
And the entire pipe support 21 is integrally fused and joined.
Increases strength.

In the above embodiment, an example of a joint that opens in two directions so as to join two pipes 8 and 9 to be joined is shown, but a pipe that branches in three or more directions may also be used. It can also be applied to a structure in which a pipe is joined to another member.

[0025]

The electrofusion joint of the present invention has a pipe support for supporting the inner surface of the pipe to be joined.
The resin that makes up the joint body and pipe support
Because such a thermoplastic resin having a slip pipe compatible,
Upon fusing, thereby preventing the deformation of the joined pipes, to prevent the outflow of the molten resin even if the plug missing or beveled, thereby retaining sufficient surface pressure, yet
The welded pipe, joint body and pipe support are
It can be physically fused to obtain a large bonding strength, and it is possible to prevent a decrease in flow paths and a short circuit of heating wires.

By using a material having a softening point higher than that of the resin forming the joint body as the pipe support,
The softening of the pipe support itself is prevented, the temperature of the molten resin layer becomes high, and even when the pipes to be joined are softened or melted, the deformation of the pipe support is prevented, and the joint strength and flow passage reduction prevention effect. Will be even higher.

[Brief description of the drawings]

FIG. 1 is a cross-sectional view of an electrofusion joint of a reference example.

FIG. 2 is a sectional view showing a use state of FIG. 1;

FIG. 3 is a cross-sectional view of an electrofusion joint of an example.

FIG. 4 is a cross-sectional view of a conventional electrofusion joint.

FIG. 5 is a cross-sectional view showing the usage state of FIG.

FIG. 6 is a cross-sectional view showing a usage state of FIG.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Electrofusion joint 2 Joint main body 3, 4 Pipe insertion hole 5, 6 Heating wire 7 Positioning protrusion 8, 9 Joined pipe 10, 11 Resin layer 13 Flow path 21 Pipe support 22 Molten resin

Claims (1)

(57) [Claims] 1. A joint body made of a thermoplastic resin having a pipe insertion hole, a heating wire provided in the vicinity of the pipe insertion hole of the joint body, and a joined pipe inserted into the pipe insertion hole. And a pipe support extending from the joint body so as to support the inner surface of the joint body and the pipe body.
Thermoplastic resin compatible with the resin forming the joint pipe
Tree made of fat and whose pipe support constitutes the joint body
Electro fusion fittings, characterized in Rukoto such a higher fat softening temperature resin.